public void Move(int dx, int dy, int height)
{
// Short circuit check - do we have to do anything anyway?
if ((dx == 0 && dy == 0) || height <= 0)
return;
if (BytesPerPixel != 1 && BytesPerPixel != 2 && BytesPerPixel != 4)
throw new NotSupportedException("Surface.Move: bytesPerPixel must be 1, 2, or 4");
// vertical movement
if (dy > 0)
{
// move down - copy from bottom to top
var dstPos = (height - 1) * Pitch;
var srcPos = dstPos - dy * Pitch;
for (var y = dy; y < height; y++)
{
Buffer.BlockCopy(Pixels, srcPos, Pixels, dstPos, Pitch);
srcPos -= Pitch;
dstPos -= Pitch;
}
}
else if (dy < 0)
{
// move up - copy from top to bottom
var dstPos = 0;
var srcPos = dstPos - dy * Pitch;
for (var y = -dy; y < height; y++)
{
Buffer.BlockCopy(Pixels, srcPos, Pixels, dstPos, Pitch);
srcPos += Pitch;
dstPos += Pitch;
}
}
// horizontal movement
if (dx > 0)
{
// move right - copy from right to left
var dstPos = (Pitch - BytesPerPixel);
var srcPos = dstPos - (dx * BytesPerPixel);
for (var y = 0; y < height; y++)
{
for (var x = dx; x < Width; x++)
{
if (BytesPerPixel == 1)
{
Pixels[dstPos--] = Pixels[srcPos--];
}
else if (BytesPerPixel == 2)
{
Array.Copy(Pixels, srcPos, Pixels, dstPos, 2);
srcPos -= 2;
dstPos -= 2;
}
else if (BytesPerPixel == 4)
{
Array.Copy(Pixels, srcPos, Pixels, dstPos, 4);
srcPos -= 4;
dstPos -= 4;
}
}
srcPos += Pitch + (Pitch - dx * BytesPerPixel);
dstPos += Pitch + (Pitch - dx * BytesPerPixel);
}
}
else if (dx < 0)
{
// move left - copy from left to right
var dstPos = 0;
var srcPos = dstPos - (dx * BytesPerPixel);
for (var y = 0; y < height; y++)
{
for (var x = -dx; x < Width; x++)
{
if (BytesPerPixel == 1)
{
Pixels[dstPos++] = Pixels[srcPos++];
}
else if (BytesPerPixel == 2)
{
Array.Copy(Pixels, srcPos, Pixels, dstPos, 2);
srcPos += 2;
dstPos += 2;
}
else if (BytesPerPixel == 4)
{
Array.Copy(Pixels, srcPos, Pixels, dstPos, 4);
srcPos += 4;
dstPos += 4;
}
}
srcPos += Pitch - (Pitch + dx * BytesPerPixel);
dstPos += Pitch - (Pitch + dx * BytesPerPixel);
}
}
}
}
